Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, non-destructive and closed-world, so the extra burden is low; the description still adds value with 'Free, no auth', which annotations do not express. It omits what happens when a record is missing, and it doesn't reconcile the fact that the schema marks zero required parameters while the text implies at least one of url or kind+slug is needed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.